Good afternoon.

I have made it so ranks "Staff" and "Owner" are green, and "default" is yellow.
I have changed priorities to
0 = default
1 = Staff
2 = Owner
But the Username and chat is still Yellow for staff.
Removing them from the default group makes them green, however upon relog, they are yellow again.

How do I fix this?

Thank you very much :)

You have your priorities inverted. The lower the number, the higher the priority.
Also, you can't remove people from the default groups (default, moderator, and admin). Oxide/uMod will automatically add you to them again.

Damn. Didn't even notice that. Thank you!